WCD-11. The Arctic Atmospheric Boundary-Layer Structure and Its Interactions with the Free Troposphere and Surface

Abstract
The atmospheric boundary layer over Arctic sea ice can conceptually be described as an ubiquitous Arctic inversion (AI) separating the free troposphere above from the sea-ice boundary below and extending to heights of 1000-1500 m. This typically stable AI inhibits vertical mixing, but is modified by the Arctic boundary layer (ABL) nearest the surface through local frictional or buoyant processes and the cloud-forced mixed layer (CML) aloft forced by cloud-top radiative cooling. When the forcing of the ABL is sufficiently strong, the ABL becomes a surface-based mixed layer (SML). While the CML and SML are generally distinct, they at times appear to couple producing a layer from the surface to cloud top with a near-neutral lapse rate throughout. Hence, during these periods, significant transport of heat, moisture, momentum, aerosols, and trace gases could occur. The formation of low-level wind jets (LLJs) within the AI also modifies its turbulent structure and enhances vertical transport. This recently funded project aims to evaluate, explore, and advance this conceptual model using the MOSAiC data set and select modeling experiments. This poster may show preliminary results, but its primary purpose is to stimulate discussion of this conceptual model and analyses needed to evaluate it.